This disclosure generally relates to calibration and/or confirming color accuracy of marking systems.
This disclosure refers to marking as a process of producing a pattern, such as text and/or images, on a substrate, such as paper or transparent plastic. A marking device performs the marking by depositing ink, toner, dye, or any other suitable marking material on the substrate. Known marking devices include xerographic marking engines and inkjet marking engines.
Various factors affect the actual color produced by a marking device in response to a given input. Thus, to achieve a desired color on a marked substrate, or rather, to get as close to the desired color as possible, typically it is necessary to perform calibration by marking test patches on a substrate, analyzing the marked test patches with a spectrophotometer or other color measuring device, and generating or updating a color calibration value or set of values such as a tone reproduction curve (TRC). The TRC is then used to alter the theoretical combination of marking material (e.g., C (cyan), M (magenta), Y (yellow) and K (black) toners or inks) to produce more accurate color on subsequently marked substrates, by mapping image data input values (e.g., RGB values) to marking device output values (e., CMYK values). A set of test patches, also known as a target or target patch pattern, can include any desired number of test patches, from one patch to over 1,000 patches, but typically includes from several dozen to several hundred test patches.